847/845: Difference between revisions

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'''847/845''', the '''cuthbert comma''', is a [[13-limit]] (also [[5.7.11.13 subgroup]]) [[comma]] measuring about 4.09{{cent}}. It is the difference between [[7/5]] and a stack of two [[13/11]]'s. It is also the difference between [[125/121]] and [[175/169]].
'''847/845''', the '''cuthbert comma''', is a [[small comma|small]] [[13-limit]] (also [[5.7.11.13 subgroup|5.7.11.13-subgroup]]) [[comma]] measuring about 4.09{{cent}}. It is the difference between [[7/5]] and a stack of two [[13/11]]'s. It is also the difference between [[125/121]] and [[175/169]].
 
In the 5.7.11.13 subgroup, it is the simplest comma of its size (and the smallest of its complexity) by an extremely large margin. For comparison, [[637/625]] is about as simple but much larger, and [[2941225/2924207]] is significantly more complex yet still twice as large.


In terms of full 13-limit commas, it is the difference between the following superparticular pairs:  
In terms of full 13-limit commas, it is the difference between the following superparticular pairs:  
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* [[385/384]] and [[4225/4224]]
* [[385/384]] and [[4225/4224]]


Meanwhile, it can be factorized as [[1001/1000]] × [[2200/2197]] or [[441/440]] × [[10648/10647]].
Meanwhile, it can be factorized as ([[1001/1000]])⋅([[2200/2197]]) or ([[441/440]])⋅([[10648/10647]]).
 
In the 5.7.11.13 subgroup, it is the simplest comma of its size (and the smallest of its complexity) by an extremely large margin. For comparison, [[637/625]] is about as simple but much larger, and [[2941225/2924207]] is significantly more complex yet still twice as large.


== Temperaments ==
== Temperaments ==
[[Tempering out]] this comma in the 13-limit results in the rank-5 cuthbert temperament and enables the [[cuthbert chords]].  
[[Tempering out]] this comma in the 13-limit results in the rank-5 '''cuthbert''' temperament and enables the [[cuthbert chords]].  


Tempering it out in the 5.7.11.13 subgroup leads to an extremely efficient rank-3 temperament.
Tempering it out in the 5.7.11.13 subgroup leads to an extremely efficient rank-3 temperament.
== See also ==
* [[Small comma]]


[[Category:Cuthbert]]
[[Category:Cuthbert]]
[[Category:Commas with unknown etymology]]
[[Category:Commas with unknown etymology]]